Jack



Oct. 6, 1970 w. E. WEBSTER u, ETAL. 3,532,322

JACK

Filed out. 19. 19e? WZZE/V E. WEBSTER I C11/612165 ,4. 05752 Y @Aw/Mz@ United States Patent f) 3,532,322 JACK Warren E. Webster II, Kettering, and Charles A. Kuster,

Madison Township, Montgomery County, Ohio, as-v signors to The Joyce-Cridland Company, Dayton, Ohio,

a corporation of Ohio Filed Oct. 19, 1967, Ser. No. 676,434 Int. Cl. B66f 3/18 U.S. Cl. 254-103 9 Claims ABSTRACT OF THE DISCLOSURE A non-rotating traveling screw is threaded on a rotating screw suspending from the top of an annular worm gear rotatably driven by a worm screw. Spherical surfaces at the top and bottom of the worm gear engage spherical surfaces of washers on the jack screw to permit deflection of the screw relative to the worrn gear. Rotary motion is transmitted from the worm gear to the jack screws by key memlbers rotatably mounted in the jack screw and having circular surfaces projecting into elongate key slots in the worm gear.

The present invention relates to a jack and more particularly to a jack of the type having a rotating screw and a non-rotating nut which travels vertically along the screw. It will become apparent, however, that the invention is not necessarily so limited.

Jack screws designed to support loads and drive the loads vertically are typically designed only to operate with the jack screw rotating about a ixed Vertical axis. There is a need, however, for jacks capable of vertically moving loads which may shift horizontally and thus cause a deflection or displacement of the jack screw. Deflection or displacement of conventional jacks results in severe wear on parts of the jack and may even result in binding of the jack mechanism.

Various designs have been proposed to provide a jack wherein the jack screw can be deflected or displaced without harm to part of the jack and without binding of the jack mechanism. Previously proposed designs are expensive to manufacture in that they require close tolerances over relatively large spherical surface areas. Also, the proposed designs have been of unusual constructions requiring a large number of parts or inherently adding to the backlash of the jack.

An object of this invention is to provide an improved jack with a jack screw which can ybe deflected or displaced spherically through small angles. This is accomplished in accordance with this invention by suspending a jack screw from the top of an annular drive member and permitting the jack screw to pivot about a point internally of the drive member. A portion of the upper surface of the drive member is spherical and a suspension member connected to the jack screw has a spherical lower surface which mates with the upper surface of the drive member.

It is a further object of this invention to provide a positive drive for the jack screw which has a minimal backlash and which does not interfere with the deflection or displacement of the jack screw permitted by its suspension. The annular drive member positively drives the jack screw -by a slot and key arrangement wherein a key is rotatably mounted about a horizontal longitudinal axis transverse to the longitudinal axis of the jack screw, the point of intersection of the longitudinal axis of the jack screw and the longitudinal axis of rotation of the key being located at the point about which the jack screw pivots. Also, the key is designed to slide in a key slot and rotate in the key slot about a horizontal axis which is transverse to both the longitudinal axis of the jack screw Nice and the longitudinal axis of the key. For balance, there are desirably two keys and two key slots symmetrically located with respect to a vertical plane passing through the vertical centerline of the jack screw.

Other objects will become apparent from the following description and the drawing in which:

FIG. 1 is a vertical section of a jack made in accordance with this invention.

FIG. 2 is an enlarged, horizontal cross sectional view of a part of the jack as viewed in the direction of arrows 2-2 of FIG. l.

FIG. 3 is an enlarged perspective view of a key used in the jack of FIG. 1.

With reference to FIG. l, the jack of this invention is generally indicated Iby the reference character 10 and includes a hollow housing, generally designated 12, having a base or body portion 14, a cap 16 threaded in the body portion 14 and an expansion plug cover 18 mounted on top of the cap 16. The housing 12 may be mounted on any suitable horizontal platform 2t) having an aperture 22 therein through which a portion of the j'ack 10 projects.

The jack 10 includes a depending threaded jack screw 24 drivingly engaged with the threads of a traveling nut 26 upon which is mounted a load support housing or the like indicated by the phantom lines 28. The load support housing 28 is adapted to support a load (not shown) which is held against rotation by means (not shown) and the load support housing 28 has slots 30 therein confining the heads of screws 32 threaded into the traveling nut 26. The arrangement of the screws 32 in the slots 30 is a conventional arrangement for restraining the nut 26 from rotation. Thus, as obvious, rotation of the jack screw 24 will cause vertical travel of the nut. 26. Although one form of traveling nut is described, it to be understood that the invention herein is not limited to any particular design of the traveling nut 26. Also, the load support housing 28 and the manner of supporting the load may take any suitable form.

Referring to the portion of the jack mechanism within the hollow housing 12 shown in FIG. 1, a lower load support bearing assembly 34 is mounted in a recess in the housing 12 and supports an annular worm gear drive member 36 for rotation about a vertical axis. The drive member 36 has an elongate, vertically extending hub 38 of reduced diameter through which extends a longitudinal jack screw receiving bore 40. The jack screw 24 is suspended from the top of the hub 38 of the drive member 36 ifor rotation about the same axis as the drive member 36 by suspension means including a suspension washer 42 threaded on the top of the jack screw 24 and held axially xed thereon as by set screws 44. The lower surface 46 of the suspension washer 42 is concavely spherical and rests upon the upper surface 48 of the hub 38 which is convexly spherical. The spherical surfaces 46 and 48 are in confronting mating engagement and the two spherical surfaces 46 and 48 have a common radius and are centered at a point within the jack screw 24 which will be further described below.

Worm gear teeth 50 peripherally extending around the center portion of the annular drive member 36 are engaged by a worm screw 52 rwhich may be driven in any suitable fashion to cause rotation of the drive member '36 about its axis. In turn the annular drive member 36 is drivingly connected to the jack screw 24 by key means comprising a pair of generally T-shaped key members 54 illustrated in FIGS. 1 and 3, each of which has a generally cylindrical leg or pin portion S6 snugly received within a transverse bore 58 in the jack screw 24 and a flat-sided head or key portion 60 which may be integral with the leg or pin portion 56. Each key portion 60 is received within a longitudinally extending key slot 62 in the hub 38 which opens to the bore 40. With reference to FIG. 2, it will be observed that there are two diametrically opposed key slots 62 snugly receiving the two key portions 60. The keys 54 are, there-fore, symmetrically located with respect to a vertical plane longitudinally bisecting the jack screw 24. For reasons which will become apparent, the top or radially outermost surfaces 64 of the head or key portions 60 are convexly arcuate or curved. The curve is such that the top surfaces 64 form part of an imaginary cylindrical ring or band centered at the same point as the `center of the spherical sun-faces 46 and 48.

In operation the jack will be mounted on the platform as shown with the jack screw normally depending vertically with its vertical axis along the centerline CL appearing in FIG. 1. Should, however, the traveling nut 26 be deflected or displaced in a horizontal direction, the centerline of the jack screw 24 may pivot in any direction about the point of intersection of the longitudinal centerline of the jack screw 24 and the longitudinal centerline of the transverse bore 58. This point is also the center of the imaginary sphere containing the surfaces 46 and 48 fwhich has diameters extending along the centerline CL and the axis of the transverse bore 58. The same point is the center of the imaginary circular band containing the top surfaces 64 of the T-shaped key members 54. The aforementioned pivotal movement or deflection of the centerline of the jack screw 24 in the plane of the drawing is indicated by the lines a and b in FIG. l. As should be obvious, the pivotal deliection or displacement of the jack screw 24 is made possible by the unique suspension of the jack screw 24 on the spherical upper surface of the hub 38. The key members 54 do not interfere with the pivotal deection or displacement of the jack screw 24 because their pin portions 56 are free to rotate within the transverse bore 58 about one horizontal axis and their circular top surfaces 64 are free to slide in the longitudinal key slots 62 and rotate about horizontal axes at the bottom of the key slots 62 which horizontal axes are transverse to the axis of rotation of the pin portions 56. Also, the clearance between the key members 54 and the key slots 62 is sufficient to permit a small relative movement therebetween.

The longitudinal bore 40 in the annular drive member 36 is defined by a downwardly converging upper conical surface y66 is a downwardly diverging lower conical surface 68 within the hub 38 so that, as apparent, the jack screw 24 is free to pivot within the bore 40. The taper of the surfaces 66 and 68 is slightly exaggerated in FIG. l for purposes of clarity. At the vertical center of the bore 40, the upper and lower conical surfaces 66 and 68 join to lform a circular surface engaging and laterally confining the jac-k screw 24. It will be appreciated that the conical surfaces 66 and 68 limit the deection of the jack screw 24. The illustrated jack 10 is designed for a spherical deflection of the screw 24 of about 3 or 4 degrees in any direction from the centerline CL, or a total deflection of 6 to 8 degrees.

As described thus far, the jack 10 is capable of causing the traveling nut 26 and, therefore, the load supported by the housing 28 to move vertically up and down, the direction of movement, of course, depending upon the direction of rotation of the Iworm screw 52. The manner of suspending the jack screw 24 by the suspension washer 42 enables the jack 10 to support and drive loads acting in tension thereon. A compression force may be applied to the jack 10* in the event a load should bottom out or in the event some other force would prevent movement of the load although the worm screw 52 is still being driven. To accommodate possible compression forces, a compression washer 70 rests upon an enlarged shoulder 72 on the screw 24 and has an upper, concavely spherical surface 74 mating with a lower, convexly spherical surface 76 formed on the hub 38. The spherical surfaces 74 and 76 are centered at the same point as the spherical surfaces 46 and 48. Thus, all of the spherical surfaces. 46, 48, 74 and 76 lie on a common imaginary sphere. Accordingly, the screw 24 may undergo deiiection or displacement whether the load is acting in tension or in compression against the jack 10. Further to accommodate a compression force, a compression thrust bearing assembly 78 is located on top of the worm gear drive member 36 and is received within a recess in the hollow housing '12, the arrangement being such that the two bearn ing assemblies 34 and 78 confine the annular drive member 36 and surround the vertically extending parts of the hub 38 thereof. It will also be noted that the suspension washer 42 and the compression washer 70 cooperate to maintain the jack screw 24 axially ixed with respect to the annular drive member 36 regardless of the direction of lforce applied to the jack screw 24.

Because the spherical surfaces 46, 48, 74 and 76 are all the same radius and are all of small area, they are relatively easily and inexpensively formed. Also, the snug tit of the key portions 60 in the key slots 62 provides a positive rotary drive for the jack screw with a minimal backlash. Those skilled in the art fwill appreciate that conventional means may be used to provide lubrication within the hollow housing 12 and to protect the jack 10 from dust or other noxious matter.

Although the presently preferred embodiment of the device has been described, it will be understood that Within the purview of this invention various changes may be made within the scope of the appended claims.

Having thus described our invention, we claim:

1. A jack of the type having a vertically oriented rotating jack screw drivingly connected to a non-rotating nut causing said nut to travel vertically along said screw, said jack comprising: an annular drive member having a longitudinal bore therethrough and an upper convexly spherical surface portion; means supporting said drive member for rotation about a vertical axis extending through said bore, means for rotating said drive member about said axis; a jack screw extending through said bore; suspension means connected to said jack screw and suspending said jack screw from the top of said drive member, said suspension means having a lower concavely spherical surface portion resting upon said upper convexly spherical surface portion of said drive member; and drive means drivingly interconnecting said drive member and said jack screw.

2. The jack of claim 1 wherein said longitudinal bore is defined by a conically downwardly converging upper surface portion and a conically downwardly diverging lower surface portion.

3. The jack of claim 1 wherein said annular drive member has peripheral worm gear teeth and an elongate vertically projecting hub of reduced diameter, and wherein said upper convexly spherical surface portion is formed on said hub.

4. The jack of claim 1 wherein said drive member has a longitudinally extending key slot opening to said bore, said jack screw has a bore extending transversely to its longitudinal axis and at least partially therethrough, and wherein said means interconnecting said drive member and said jack screw includes a key member having a pin portion received within said bore in said jack screw and a key portion confined within said key slot.

5. The jack of claim 4 wherein said spherical surface portions are formed on a common imaginary sphere centered within said jack screw, wherein said bore in said jack screw has a central longitudinal axis extending substantially along a diameter of said sphere, and wherein said pin portion of said key member is rotatable about said central longitudinal axis of said bore in said jack screw.

6. The jack of claim 5 wherein said key portion has a radially outermost surface within said key slot which lies in a circular arc centered at the same point as said imaginary sphere.

7. A jack of the type having a vertically oriented jack screw drivingly connected to a non-rotating nut causing said nut to travel along said screw, said jack comprising: an annular drive member having a longitudinal bore therein and a longitudinally extending key slot opening to said bore, means supporting said drive member for rotation about a rst axis, means for rotating said drive member about said rst axis, a jack screw extending through said bore, said jack screw having a transverse bore extending at least partially therethrough, means supporting said jack screw in axially fixed relation to said annular drive member and supporting said jack screw for pivotal movement relative to said drive member about a point located substantially at the intersection of said first axis and the longitudinal axis of said transverse bore, and drive means drivingly interconnecting said annular drive member and said jack screw, said drive means including a key member having a pin portion rotatably received within said transverse bore and a key portion confined Within said key slot.

8. The jack of claim 6 wherein said key portion has a substantially circularly curved surface within said key slot.

9. The jack of claim 7 wherein said longitudinal bore is defined by a conically downwardly converging upper surface portion and a conically downwardly diverging lower surface portion.

References Cited UNITED STATES PATENTS 2,069,603 2/1937 Barley 64-7 3,204,427 9/ 1965 Dunn 64--8 3,339,892 9/1967 Dixon 254-103 OTHELL M. SIMPSON, Primary Examiner D. R. MELTON, Assistant Examiner 

